Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover readOnly, idempotent, non-destructive, and closed-world, so the safety profile is done. The description adds useful behavioral detail beyond that: it discloses the returned payload (price, date, week, previous figure, trend as sube/baja/repite, source, licence, and a link with chart and history).

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The first sentence is dense, front-loaded, and information-rich, but the trailing Spanish sentence mostly restates it ('Último precio de una serie o de un producto, con su fuente y su fecha'), adding only the words 'source' and 'date', which were already present. Bilingual duplication costs space without adding agent-relevant meaning.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only lookup tool with zero required parameters and no output schema, the description covers both input modes and enumerates the return payload, which is what an agent needs before calling it. Only the routing against sibling tools is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3. The description reinforces the serie-versus-producto semantics ('by its identifier' versus 'products matching a text') but adds nothing about ambito, limite, or whether serie and producto are mutually exclusive.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a specific resource and verb: 'Latest published price' of a series or of products matching a text. It clearly distinguishes the two lookup modes (exact identifier versus text search). It does not differentiate itself from siblings such as buscar_producto or historico, which likely overlap with the text-search path.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The two modes (identifier versus text) imply when to use the tool, and the schema notes that 'producto' is for when the identifier is unknown. However, the description never names alternatives like historico (for history) or buscar_producto (for discovery), nor states any exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.